A Queens man who traveled overseas to train with al Qaeda and returned planning to launch suicide bomb strikes in New York City’s subways was convicted today in what federal officials have called the biggest terror threat on US soil since 9/11.

Adis Medunjanin, 28, who faces life in prison when he sentenced Sept. 7, was found guilty of conspiring to use weapons of mass destruction and conspiring to murder U.S. military personnel overseas, among other charges.

Wearing a dark suit and gray tie, the bearded Medunjanin glanced back several times at his family in the gallery, seemingly trying to gauge their reactions, as the jury foreman rattled off nine verdicts of “Guilty.”

As the verdicts were being read, Medunjanin appeared to be praying, holding his hands out in front of his body.

Afterward, the former Manhattan building worker asked his lawyer Robert Gottlieb to “tell his family to continue be strong,” the lawyer said.

Jurors declined to comment, but Medunjanin’s anguished sister broke down in tears and screamed, “Oh God! Oh God!” as she left court.

The terror plotter was born in Bosnia, but moved to the US as a young boy with his parents to escape ethnic cleansing in the civil war chaos of a fragmented Yugoslavia.

He grew up with his family in Queens, attended Flushing High School, and graduated from Queens College with a bachelor’s degree in economics.

As he reached adulthood, Medunjanin gravitated towards a world view that was at odds with American foreign policy in the Middle East, and became convinced that the West was persecuting Muslims, defense attorney Robert Gottlieb told the jury.

“His plan, his intent, was to go to Afghanistan and fight with the Taliban,” Gottlieb said at trial.

But when that plan faltered, Medunjanin and two former high school classmates were recruited by al Qaeda spotters in Pakistan who saw extraordinary value in their US passports and the ease with which they could cross borders in a post 9-11 security environment, Brooklyn federal prosecutors said.

Although the trio from New York insisted they wanted to join the Taliban, the al Qaeda operatives in 2008 repeatedly urged them to return to the US and carry out “martyrdom operations” or suicide attacks.

Medunjanin’s friend and fellow plotter, Najibullah Zazi, testified at the trial that he felt al Qaeda had “brainwashed” him into becoming a suicide bomber.

Zazi recounted how he, Medunjanin, and another New Yorker, Zarein Ahmedzay, were tutored in terror tactics at an al Qaeda compound in Wazirstan, in Pakistan’s western tribal region, and later Zazi learned how to make explosives from household chemicals.

Both Zazi and Ahmedzay pled guilty and agreed to cooperate with the feds.

An FBI expert told the jury that the backpack bombs the trio planned to detonate would have caused significant destruction and death in a subway car, killing anyone near the bomber, with shrapnel and shredded pieces of the subway car’s interior fatally cutting down many others.

After returning to the US, Zazi said he built a detonator bomb, rented a car in Denver, and drove to New York, where he met with Medunjanin and Ahmedzay to carry out the strikes in the subway lines beneath Grand Central Station.

But the FBI and NYPD arrested them in Jan. 2010 before they could launch the attacks.